1. Field of the Invention
The present invention relates generally to a safety belt retractor, and more particularly, toward safety belt retractors having a lap belt and a shoulder belt in a single housing, wherein locking of both belts is responsive to vehicle acceleration forces acting on a single sensor.
2. Description of the Prior Art
In a typical safety belt system for a vehicle, retractable lap and shoulder belts are provided to secure a passenger in position on a seat in the event of collision. When not in use, the lap and shoulder belts are retracted by spiral wound helical-type springs and stored in helical wrap in separate safety belt retractor mechanisms. The lap belt retractor is generally positioned adjacent one side of the passenger, for example on the floor, and the shoulder belt retractor is located behind the occupant for example on the pillar or on the roof of the vehicle. The free ends of the lap and shoulder belts may be connected together for coupling to a common buckle or belt receptacle positioned on the seat at the opposite side of the passenger.
In early safety belt retractors, the length of the safety belt is manually adjusted by each passenger prior to use using a belt take-up device. In order to provide a safety belt retractor that accomodates all passengers without the need for individual length adjustment, vehicle inertia responsive retractors have been developed. In these retractors, a belt spool is continuously spring-biased in a retracting direction and one end of the spool has a set of ratchet teeth adapted to engage with a pawl for locking the spool against belt withdrawal. During normal driving, the pawl is maintained separated from the ratchet by a vertically suspended pendulum-type inertia device. In response to excessive acceleration of the vehicle, that is, sharp increases or decreases in speed or sharp cornering, the pendulum pivots the pawl into engagement with the ratchet teeth on the spool preventing pay out of the belt.
While the inertia responsive lap and shoulder belt retractors have been generally satisfactory, the provision of two separate safety belt retractors has increased cost and has required additional space utilization. In order to minimize costs and to free up the space occupied by the second retractor, it has been proposed to mount both the lap and shoulder belt in a single housing. In U.S. Pat. No. 3,974,979 to Fieni, a single pawl is positioned between a pair of spools in tandem carrying the lap and shoulder belts. The pawl is pivotably supported within the housing equispaced between the spools, and is operative to engage a set of ratchet teeth on each spool. Engagement and disengagement of the pawl are manually controlled by the passenger; the retractor is not vehicle inertia responsive.
Accordingly, there exists a need for a lap and shoulder belt retractor wherein locking and unlocking of the belts are automatically controlled in response to vehicle acceleration. In order to reduce costs, there exists a further need for such a retractor wherein only a single inertia responsive device is operative with both belts.
One object of the present invention, therefore, is to provide a tandem spool, vehicle responsive inertia retractor for storing the lap and shoulder belts.
Another object of the invention is to provide a new and improved lap and shoulder retractor that accomodates passengers without requiring manual length adjustment.
Another object of the invention is to provide a new and improved retractor for both the lap and shoulder safety belts, wherein the lap and shoulder belts are stored within a single housing and the belts are locked against withdrawal by a common inertia responsive device.